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Hi Zhang,

Please help...

Thanks.
jung

Hi Zhang,

Attachment size is just 5mb. Note that, it is working before and just recently experienced the error. Another thing is that, outlook is able to send email without attachment.

another weird thing is, sometimes outlook is able to send email even with attachment but sometimes it's landed on "outbox" and never push through and receiving the below error:
"Task 'jung@mydomain.com - Sending' reported error (0x800CCC0F) : 'The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).'"

Note:
a. Sending email using browser doesn't have any issues at all.
b. Iredmail is using a self-signed certificate only.

Please find below postconf:

root@bit:~# postconf -n
alias_database = hash:/etc/postfix/aliases
alias_maps = hash:/etc/postfix/aliases
allow_min_user = no
allow_percent_hack = no
biff = no
body_checks = pcre:/etc/postfix/body_checks.pcre
command_directory = /usr/sbin
compatibility_level = 2
content_filter = smtp-amavis:[127.0.0.1]:10024
daemon_directory = /usr/lib/postfix/sbin
data_directory = /var/lib/postfix
debug_peer_level = 2
debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5
disable_vrfy_command = yes
dovecot_destination_recipient_limit = 1
enable_long_queue_ids = yes
enable_original_recipient = no
header_checks = pcre:/etc/postfix/header_checks
inet_interfaces = all
inet_protocols = all
lmtp_tls_mandatory_protocols = !SSLv2 !SSLv3
lmtp_tls_protocols = !SSLv2 !SSLv3
mail_owner = postfix
mailbox_size_limit = 52428800
mailq_path = /usr/bin/mailq
message_size_limit = 52428800
mlmmj_destination_recipient_limit = 1
mydestination = $myhostname, localhost, localhost.localdomain
mydomain = mydomain.com
myhostname = mydomain.com
mynetworks = 127.0.0.1 [::1]
myorigin = mydomain.com
newaliases_path = /usr/bin/newaliases
postscreen_access_list = permit_mynetworks cidr:/etc/postfix/postscreen_access.cidr
postscreen_blacklist_action = drop
postscreen_dnsbl_action = drop
postscreen_dnsbl_reply_map = texthash:/etc/postfix/postscreen_dnsbl_reply
postscreen_dnsbl_sites = zen.spamhaus.org=127.0.0.[2..11]*3 b.barracudacentral.org=127.0.0.2*2
postscreen_dnsbl_threshold = 2
postscreen_dnsbl_whitelist_threshold = -2
postscreen_greet_action = drop
proxy_read_maps = $canonical_maps $lmtp_generic_maps $local_recipient_maps $mydestination $mynetworks $recipient_bcc_maps $recipient_canonical_maps $relay_domains $relay_recipient_maps $relocated_maps $sender_bcc_maps $sender_canonical_maps $smtp_generic_maps $smtpd_sender_login_maps $transport_maps $virtual_alias_domains $virtual_alias_maps $virtual_mailbox_domains $virtual_mailbox_maps $smtpd_sender_restrictions $sender_dependent_relayhost_maps
queue_directory = /var/spool/postfix
recipient_bcc_maps = proxy:mysql:/etc/postfix/mysql/recipient_bcc_maps_user.cf proxy:mysql:/etc/postfix/mysql/recipient_bcc_maps_domain.cf
recipient_delimiter = +
relay_domains = $mydestination proxy:mysql:/etc/postfix/mysql/relay_domains.cf
sender_bcc_maps = proxy:mysql:/etc/postfix/mysql/sender_bcc_maps_user.cf proxy:mysql:/etc/postfix/mysql/sender_bcc_maps_domain.cf
sender_dependent_relayhost_maps = proxy:mysql:/etc/postfix/mysql/sender_dependent_relayhost_maps.cf
sendmail_path = /usr/sbin/sendmail
setgid_group = postdrop
show_user_unknown_table_name = no
smtp-amavis_destination_recipient_limit = 1
smtp_tls_CAfile = $smtpd_tls_CAfile
smtp_tls_CApath = /etc/ssl/certs
smtp_tls_loglevel = 1
smtp_tls_mandatory_protocols = !SSLv2 !SSLv3
smtp_tls_note_starttls_offer = yes
smtp_tls_protocols = !SSLv2 !SSLv3
smtp_tls_security_level = may
smtpd_command_filter = pcre:/etc/postfix/command_filter.pcre
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_end_of_data_restrictions = check_policy_service inet:127.0.0.1:7777
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks permit_sasl_authenticated check_helo_access pcre:/etc/postfix/helo_access.pcre reject_non_fqdn_helo_hostname reject_unknown_helo_hostname
smtpd_recipient_restrictions = reject_non_fqdn_recipient reject_unlisted_recipient check_policy_service inet:127.0.0.1:7777 permit_mynetworks permit_sasl_authenticated reject_unauth_destination check_policy_service inet:127.0.0.1:12340
smtpd_reject_unlisted_recipient = yes
smtpd_reject_unlisted_sender = yes
smtpd_sasl_path = private/dovecot-auth
smtpd_sasl_type = dovecot
smtpd_sender_login_maps = proxy:mysql:/etc/postfix/mysql/sender_login_maps.cf
smtpd_sender_restrictions = reject_non_fqdn_sender reject_unlisted_sender permit_mynetworks permit_sasl_authenticated check_sender_access pcre:/etc/postfix/sender_access.pcre reject_unknown_sender_domain
smtpd_tls_CAfile = /etc/ssl/certs/iRedMail.crt
smtpd_tls_CApath = /etc/ssl/certs
smtpd_tls_cert_file = /etc/ssl/certs/iRedMail.crt
smtpd_tls_dh1024_param_file = /etc/ssl/dh2048_param.pem
smtpd_tls_dh512_param_file = /etc/ssl/dh512_param.pem
smtpd_tls_exclude_ciphers = aNULL, eNULL, EXPORT, DES, RC4, MD5, PSK, aECDH, EDH-DSS-DES-CBC3-SHA, EDH-RSA-DES-CDC3-SHA, KRB5-DE5, CBC3-SHA
smtpd_tls_key_file = /etc/ssl/private/iRedMail.key
smtpd_tls_loglevel = 1
smtpd_tls_mandatory_protocols = !SSLv2 !SSLv3
smtpd_tls_protocols = !SSLv2 !SSLv3
smtpd_tls_security_level = may
swap_bangpath = no
tls_random_source = dev:/dev/urandom
transport_maps = proxy:mysql:/etc/postfix/mysql/transport_maps_user.cf proxy:mysql:/etc/postfix/mysql/transport_maps_maillist.cf proxy:mysql:/etc/postfix/mysql/transport_maps_domain.cf
unknown_local_recipient_reject_code = 550
virtual_alias_domains =
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql/virtual_alias_maps.cf proxy:mysql:/etc/postfix/mysql/domain_alias_maps.cf proxy:mysql:/etc/postfix/mysql/catchall_maps.cf proxy:mysql:/etc/postfix/mysql/domain_alias_catchall_maps.cf
virtual_gid_maps = static:2000
virtual_mailbox_base = /var/vmail
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql/virtual_mailbox_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql/virtual_mailbox_maps.cf
virtual_minimum_uid = 2000
virtual_transport = dovecot
virtual_uid_maps = static:2000

Thanks,
JunG